Limit adjustment means for a rotatable control



March 1965 s. J. TEMPLE 3,176,107

LIMIT ADJUSTMENT MEANS FOR A ROTATABLE CONTROL Filed Feb. 13, 1962 INVENTOR. SnvuarJ TEMPLE A TTORA/E/s United States Patent 3,176,107 LIMIT ADJUSTMENT MEANS FOR A ROTATABLE CONTROL Sidney J. Temple, Pittsburgh, Pa., assignor to Edwin L. Wiegaud Company, Pittsburgh, Pa.

Filed Feb. 13, 1962, Ser. No. 173,097 2 Claims. (Cl. 200-166) My invention relates to rotatable controls, more particularly to thermostats having a rotatable member for setting the thermostat, and the principal object of my invention is to provide new and improved devices of the character described.

In the drawing accompanying this specification and forming a part of this application, there is shown, for purposes of illustration, an embodiment which my invention may assume, and in this drawing:

FIGURE 1 is a fragmentary front view of a switch embodying my invention, the control knob having been removed,

FIGURE 2 is a fragmentary side elevational view of the switch, and

FIGURE 3 is a separated perspective view of parts comprising the invention.

My invention is herein disclosed in a thermostatic switch, although it should be understood that the invention may be applied to any type of rotatable control. The disclosed switch comprises a body which contains the usual switch contacts (not shown) and has a capillary tube 11 leading from the body 10 and terminating in the usual sensing element (not shown).

A rotatable shaft 12 is carried by the body 10 for the purpose of adjusting the switch contacts to respond to selected predetermined conditions. In the disclosed construction, the body 10 has a bracket 14 extending forwardly therefrom and serving to provide a ready connection with a mounting panel 15, the connection being indicated by machine screw 16 passing through openings in the panel and received in screw-threaded apertures 17 in oppositely extending ears 1818 which are offset from the central portion 19 of the bracket to provide shoulders 2020 therebetween.

The shoulders 20 are apertured, as at 21, a lug 22 extending into the aperture in the lower shoulder and forming a fixed stop, for a purpose to be described. Secured to the shaft 12, for rotation therewith, is a washer-like member 23 having a finger 24 extending radially therefrom. The apertures 21 in the shoulders 20 provide space for rotation of the finger 24.

In the position of parts shown in FIGURE 3, one edge 24a, of the finger 24 engages the lug 22 to limit rotation of the shaft in a counter clockwise direction and this may represent the off position of the thermostat wherein the switch contacts are in open position. Rotation of the shaft 12 in a clockwise direction will set the thermostatic switch so that the switch contacts are under control of thermal conditions detected by the sensing element and transmitted through the capillary tube to the usual actuator for the switch contacts.

Rotation of the shaft 12 to a selected set position accordingly adjusts the usual switch actuator (in known manner) so that the switch contacts are opened when the selected temperature is reached. It is desirable to be able to change the set position so that the switch will 3,176,107 Patented Mar. 30, 1965 respond to a selected temperature. A knob 25, of usual construction, may be removably connected to the shaft 12 to rotate the same, the knob having temperature indicia thereon, as seen in FIGURE 2.

The finger 24 is removed from engagement with the lug 22 in the position shown in FIGURE 3 by rotation of the shaft in a clockwise direction, the opposite finger edge 24b engaging the lug 22 after almost 360 of rotation to thus limit rotation of the shaft. In order to limit rotation of the shaft 12 to a selected lesser degree, a different washer 23 was heretofore required to replace the washer disclosed, the replacing washer having a wider finger to provide a greater distance between edges 24a and 24b. This type of adjustment was not desirable or convenient because it required use of various washers 23 and also required considerable time and labor to replace washers.

In accordance with the present invention a second washer 26 is provided, this washer having a central opening 27 to freely pass the shaft 12. A tab 28 is struck from the washer to project transversely therefrom and form an abutment engageable with the finger 24. The washer 26 may be held against rotation in any selected position by the tightening of a machine screw 29 which is threaded into an opening 30 in the lower ear 18. The head 31 of the screw firmly clamps the washer between it and the adjoining face of the ear. To change the setting of the washer 26, it is merely necessary to remove the knob 25, loosen the screw 29, rotate the washer 26 to its new position, and then tighten the screw and replace the knob. The abutment 28 may therefore be disposed at any desired position along the circular path of the finger 24.

My invention makes it possible to easily and accurately adjust the position of the abutment 28. For this purpose, the shaft 12 is rotated in a counter clockwise direction untilthe edge 24a of the finger 24 engages the lug 22. This, it will be assumed, determines the o position of the thermostat. The screw 29 is then loosened and the washer 26 is rotated in a counter clockwise direction until its abutment 28 engages the edge 24b of the finger 24.

The knob 25 is then replaced and the shaft 12 is rotated until the desired temperature setting on the knob is aligned with the cooperating marking point (not shown) on the panel. By means of this action, the finger 24 has rotated the abutment 28 to the desired position. The knob 25 is then removed, the screw 29 tightened and the knob replaced, the abutment 28 thereafter forming a fixed stop to limit rotation of the shaft from off position to the set position selected.

In view of the foregoing, it will be apparent to those skilled in the art that I have accomplished at least the principal object of my invention and it will also be apparent to those skilled in the art that the embodiment herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence it will be appreciated that the herein disclosed embodiment is illustrative only, and that my invention is not limited thereto.

I claim:

1. In combination: a sheet-metal support bracket having an intermediate portion olfset from the plane of its Z,v end-'portions-to form shoulderstherebetween, said shoulders being apertured and one providinga fixed stop within its aperture, a rotatable shaft extending through an open ing in said intermediate portion, a washer-like member carried by and rotatable with said shaft and having a radial finger movable throughsaid shoulder apertures and engageable with said fixedstop to limit rotation of said shaft, a washer having an opening through which said shaft extends, said washer spanning said offset bracket portion and having a tab engageable with said finger to 10 limit'rotation of said shaft, and means'for holding-said washer in a selected rotated position about said shaft,

4 whereby the position of said, tab may be adjusted to limit rotation of said finger to a selected amount.

2. The construction of claim 1 wherein said holding means comprises a machine screw threaded into a hole in said bracket at the periphery of said Washer, to clamp a peripheral portion of said washer between said bracket and the head of said screw.

References Cited in the'file of this patent UNITED STATES PATENTS 

1. IN COMBINATION: A SHEET-METAL SUPPORT BRACKET HAVING AN INTERMEDIATE PORTION OFFSET FROM THE PLANE OF ITS END PORTIONS TO FORM SHOULDERS THEREBETWEEN, SAID SHOULDERS BEING APERTURED AND ONE PROVIDING A FIXED STOP WITHIN ITS APERTURE, A ROTATABLE SHAFT EXTENDING THROUGH AN OPENING IN SAID INTERMEDIATE PORTION, A WASHER-LIKE MEMBER CARRIED BY AND ROTATABLE WITH SAID SHAFT AND HAVING A RADIAL FINGER MOVABLE THROUGH SAID SHOULDER APERTURES AND ENGAGEABLE WITH SAID FIXED STOP TO LIMIT ROTATION OF SAID SHAFT, A WASHER HAVING AN OPENING THROUGH WHICH SAID SHAFT EXTENDS, SAID WASHER SPANNING SAID OFFSET BRACKET PORTION AND HAVING A TAB ENGAGEABLE WITH SAID FINGER TO LIMIT ROTATION OF SAID SHAFT, AND MEANS FOR HOLDING SAID WASHER IN A SELECTED ROTATED POSITION ABOUT SAID SHAFT, WHEREBY THE POSITION OF SAID TAB MAY BE ADJUSTED TO LIMIT ROTATION OF SAID FINGER TO A SELECTED AMOUNT. 